In the context of Internet Protocol (IP) networks, congestion control is handled at the transport layer, e.g. by the Transmission Control Protocol (TCP). TCP congestion control mostly relies on an implicit congestion indication in the form of lost packets. Mechanisms for explicit congestion notification (ECN) have been proposed and standardized, requiring intermediate packet switches (routers) to explicitly mark bits in the IP header of a packet indicating the incidence of congestion on the path of the packet. The notifications are reflected back by the receiver in the headers of acknowledgment or other packets flowing in the opposite direction. ECN has seen limited deployment and in some networks has shown benefits compared to packet loss and implicit congestion detection. However, there are no mechanisms indicating congestion at the receiving and/or sending node. A window flow control mechanism is available in TCP and is limited to controlling buffer use at the receiving end. Moreover, it is often the case that flow control windows are sized without relation to the available resources at the receiver, such as memory, in part to improve performance when multiple connections are established, but the different connections are active at different times.